A backup plan is useful only if the people in the interview know how to follow it. Keep the plan short. Name the primary recording, the backup method and the person who checks that the files exist.
Agree before the guest arrives
For a two-person conversation, the primary system may save separate tracks. A backup could be a second local recording, if the devices and software can safely record at the same time. Test that combination first. Two tools competing for one microphone can create a new problem.
Use a short practice take. Stop both recordings and locate both saved files. Open them and listen. Seeing a running timer during the take is not proof that a usable file was saved.
Give the files simple names that include the session date and speaker. Keep test recordings in a clearly marked test folder so the final tracks are not buried among them.
Write a disconnect rule
Decide whether people should keep recording if the call drops, and how the host will contact them. A short text message can be a useful fallback, but do not rely on an unfamiliar channel during the problem.
After the interview, ask each person to confirm that their recording is saved before disconnecting equipment. Copy the files to the agreed storage location and check the copies. Avoid deleting a backup just because the first file looks large enough.
The backup does not need to be as convenient as the main workflow. It needs to preserve enough clear audio to finish the episode. Review the plan after one practice session, while mistakes are inexpensive to fix.